Gas line weldment design and process for cvd aluminum

ABSTRACT

A system of gas lines for a processing chamber and a method of forming a gas line system for a processing chamber are provided. The system of gas lines includes electropolished multi-way valves that connect electropolished linear gas lines. By using multi-way valves rather than tee-fittings and electropolishing the linear gas lines, the nucleation of contaminating particles in the system of gas lines may be reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 60/703,379, filed Jul. 27, 2005, which is herein incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to the design ofgas line systems for chemical vapor deposition chambers.

2. Description of the Related Art

Sub-quarter micron multilevel metallization is one of the keytechnologies for the next generation of very large scale integration(VLSI). The multilevel interconnects that lie at the heart of thistechnology require planarization of high aspect ratio apertures,including contacts, vias, lines or other features having aperture widthsless than 0.25 μm and aperture depths greater than the aperture widths.Reliable formation of these interconnects is very important to thesuccess of VLSI and to the continued effort to increase circuit densityand quality on individual substrates and die.

Metal interconnects are typically formed by physical vapor deposition(PVD), chemical vapor deposition (CVD), electrochemical depositionand/or sequential combinations thereof. CVD metal films, such as CVDaluminum films, provide excellent conformal coverage of features. CVD ofaluminum films is typically performed with a bubbled precursor which istransported by means of a carrier gas into the reactor via a gas linesystem. The bubbled precursor is typically directed though a gasdistribution assembly including a showerhead and a blocker platesituated near the top of the chamber. The precursor reacts to form alayer of material on the surface of a substrate that is positioned on asubstrate support in the chamber.

The bubbled precursor is introduced into the gas distribution assemblyfrom a system of gas lines that connects sources of the precursor gasand carrier gas to the gas distribution assembly. FIG. 1 illustrates aprior art gas line design 500 having flange connectors for connectinggas sources to a CVD chamber. Flange connectors 502 and 521 connect thegas lines to a nitrogen purge gas source 503. Flange connectors 504 and523 connect the gas lines to a precursor ampoule 505. Flange connectors506 and 525 connect the gas lines to a CVD chamber 507. Flangeconnectors 508 and 527 connect the gas lines to a bypass line 509.Flange connectors 510 and 529 connect the gas lines to a pressure gauge511. The prior art gas line design includes 3 tee-fittings 512 and threeshut-off valves 514 that may trap precursors from the gas source suchthat material is undesirably deposited in the gas line. The prior artgas line design further comprises flange connectors 520, 522, 524, 526,528, and 530.

The prior art gas line design also includes twenty weldments 516. Theweldments typically provide rough surfaces inside the gas lines.Accumulation of aluminum particles on the weldments fromaluminum-containing precursors flowed through the gas lines has beenobserved. The generation of the contaminating particles may beaccelerated depending on the choice of the CVD precursor gas. Over time,the accumulation of the particles on the weldment surfaces inside thegas lines can affect the flow of precursors through the gas lines. Also,particles may flake off and be carried downstream to the chamber andcause damage to other chamber components.

Therefore, there remains a need for a method of reducing the formationof contaminating deposits or particles in gas line systems for chemicalvapor deposition chambers.

SUMMARY OF THE INVENTION

The present invention generally provides a system of gas lines for aprocessing chamber that minimizes the nucleation of contaminatingparticles in the system. In one embodiment, a system of gas lines for aprocessing chamber comprises one or more electropolished valves that arethree-way valves or higher and comprise outputs, wherein each output ofeach valve is welded to a flange connector. The system further comprisesone or more electropolished linear gas lines, wherein each of theelectropolished linear gas lines comprises a first end, a second end, afirst flange connector welded to the first end, and a second flangeconnector welded to the second end, and wherein either the first orsecond flange connector of each of the one or more electropolishedlinear gas lines is connected to one of the flange connectors welded tothe one or more electropolished valves.

In another embodiment, a system of gas lines for a processing chambercomprises two or more electropolished linear gas lines comprising afirst gas line and a second gas line, wherein the first gas line and thesecond gas line are connected at an angle by an electropolished valve.The electropolished valve is a three-way valve or higher and comprisesfirst and second outputs, wherein the first gas line is connected to thefirst output of the electropolished valve by a first flange connector onthe first output of the electropolished valve, and the second gas lineis connected to the second output of the electropolished valve by asecond flange connector on the second output of the electropolishedvalve.

In further embodiments, a method of reducing particle contamination in achemical vapor deposition chamber by minimizing the formation ofparticles in the gas line that connects the gas source to the chemicalvapor deposition chamber is provided by using three-way valves andsegments that are easily electropolished. In one embodiment, a method offorming a gas line system for a processing chamber comprises obtainingone or more electropolished valves that are three-way valves or higherand comprise outputs, wherein each output of each valve is welded to aflange connector. The method further comprises obtaining one or moreelectropolished linear gas lines, wherein each of the electropolishedlinear gas lines comprises a first end, a second end, a first flangeconnector welded to the first end, and a second flange connector weldedto the second end and then joining at least one of the electropolishedvalves to at least one of the electropolished linear gas lines bycoupling one of the flange connectors on the at least oneelectropolished valve to the first flange connector on the at least oneelectropolished linear gas line.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 (Prior Art) is a schematic drawing of a gas line design accordingto the prior art.

FIG. 2 is a schematic drawing of a gas line design according to anembodiment of the invention.

FIG. 3 is a graph showing the roughness of electropolished components ofgas line systems according to embodiments of the invention.

DETAILED DESCRIPTION

Embodiments of the present invention provide a gas line design for aprocessing chamber and a method of reducing particle contamination in aprocessing chamber by minimizing the formation of deposits in gas linesthat connect gas sources to the processing chamber. The processingchamber may be a chemical vapor deposition chamber, such as an aluminumCVD chamber. An example of an aluminum CVD chamber is an AxZ chamber,available from Applied Materials, Inc. of Santa Clara, Calif., which maybe used to deposit aluminum from the precursor 1-methylpyrrolidine alane(MPA), for example.

In one embodiment, a system of gas lines for a processing chamber isprovided. The system comprises one or more electropolished multi-wayvalves and one or more electropolished linear gas lines. For example,the system may comprise two or more electropolished linear gas linescomprising a first electropolished gas line connected to a secondelectropolished gas line at an angle by an electropolished multi-wayvalve. As defined herein, connected “at an angle” refers to a connectionthat joins two elements that are not linear with respect to each other,i.e., at an angle other than 180° with respect to each other.

The one or more electropolished multi-way valves may be three-way valvesor higher, such as four-way valves. Each output of the multi-way valvesis welded to a different flange connector. The multi-way valves areelectropolished after the flange connectors are welded to the outputs.Electropolishing smooths the inner surfaces of the multi-way valves,including inner surfaces at the weldments. The electropolished three-wayvalves described herein may be obtained from Parker HannifinCorporation, Veriflo Division, of Richmond, Calif.

The one or more electropolished linear gas lines are made by cuffing alinear piece of tubing to a desired length and welding a first flangeconnector to a first end of the tubing and welding a second flangeconnector to a second end of the tubing. An example of a tubing materialthat may be used is Valex spec 401. Examples of flange connectors thatmay be used on the multi-way valves and the linear tubings are HTCVV316L BS3-E flange connectors. The flange connectors may be glands.

After the flange connectors are welded to the ends of the tubings thatare prepared to form the desired gas lines, the inner surfaces of thelines are electropolished and passivated to form smoother innersurfaces, e.g., weldment zone areas and the adjacent heated affectedzone areas, that are more resistant to particle formation thereon. Forexample, the surface roughness in the weldment zone areas may be reducedby a factor of two. Prior to electropolishing, the weldment zone areasare typically the roughest areas, and the roughness decreases over theadjacent heat affected zone area. In one aspect, the electropolishingand passivation provides a chrome oxide coating on the inner surfaces ofthe gas lines. The electropolishing and passivation may also remove freeiron from the inner surfaces of the lines and create a chromium richsurface having a Cr/Fe ratio of greater than about 1.5. Removal of freeiron is desirable as iron may provide nucleation sites for contaminatingparticles. The chrome oxide coating may be followed by a nitric acidtreatment. The electropolishing and passivation also remove wasteby-products that are deposited on the inner surfaces during the weldingof the lines. The linear gas lines may be easily electropolished afterthe flange connectors are welded to the ends of the gas lines, as thegas lines are linear. The gas lines may be electropolished for a periodof time, such as between about 3 minutes and about 4 minutes, usingstandard electropolishing techniques. The gas lines may be polished tohave a Ra max of 5, for example. An example of a company that provideselectropolishing services for linear gas lines is IntegratedManufacturing Technologies of Fremont, Calif.

Thus, as described above, one embodiment of the invention provides amethod of forming a gas line system for a processing chamber, comprisingobtaining one or more electropolished multi-way valves and one or moreelectropolished linear gas lines and joining at least one of theelectropolished valves to at least one of the electropolished linear gaslines by coupling a flange connector on an output of the at least oneelectropolished valve to a flange connector on an end of the at leastone electropolished linear gas line. For example, two electropolishedlinear gas lines may be joined by one electropolished valve at angle,such as an angle of approximately 90°.

FIG. 2 illustrates a gas line design 600 for connecting a gas source toa CVD chamber according to an embodiment of the invention. Thecomponents of gas line design 600 will be briefly listed first, and thenthe connection between the components will be described in more detailbelow. Gas line design 600 also includes flange connectors. Flangeconnectors 602 and 621 connect the gas lines to a nitrogen purge gassource 603. Flange connectors 604 and 623 connect the gas lines to aprecursor ampoule 605, which may provide an aluminum source, forexample. Flange connectors 606 and 625 connect the gas lines to a CVDchamber 607. Flange connectors 608 and 627 connect the gas lines to abypass line 609. Flange connectors 610 and 629 connect the gas lines toa pressure gauge 611. Three-way valves 612 are used to connect the gaslines instead of tee-fittings, which reduces the amount of “dead space”that may trap precursors, and the three-way valves provide moreeffective purging of any precursors that are trapped in the lines. Inanother embodiment, four-way valves may be used. The gas line design 600includes weldments 616, but the number of weldments is reduced to 13from the twenty weldments 516 in the gas line design 500 of FIG. 1. Thegas line design 600 further includes flange connectors 620, 622, 624,626, 628, 630, 632, and 634. The flange connectors 620, 622, 624, 626,628, 630, 632, and 634 provide detachable or reversible connections. Theflange connectors may be bolted together and then unbolted to separatethe gas lines therebetween. Thus, for example, gas line 640 betweenflange connectors 626 and 628 may be removed easily and electropolished.A similar gas line 540 in the prior art gas line design 500 cannot beeasily removed and electropolished as it is located between weldments516.

The connections between the components of the gas line design 600 willnow be described in more detail. The gas line design 600 provides asystem of gas lines comprising a first linear gas line 638, a secondlinear gas line 640, a first three-way valve 642, a second three-wayvalve 644, and a third three-way valve 646. The first linear gas line638 comprises flange connector 604 welded to one end and a flangeconnector 620 welded to the other end. The second linear gas line 640comprises flange connector 626 welded to one end and a flange connector628 welded to the other end.

The first three-way valve 642 comprises a first output 648, a secondoutput 650, and a third output 652. Flange connector 622 is welded tothe first output 648. Flange connector 602 is welded to the secondoutput 650. Flange connector 624 is welded to the third output 652.

The second three-way valve 644 comprises a first output 654, a secondoutput 656, and a third output 658. Flange connector 630 is welded tothe first output 654. Flange connector 632 is welded to the secondoutput 656. Flange connector 606 is welded to the third output 658.

The third three-way valve 646 comprises a first output 660, a secondoutput 662, and a third output 664. Flange connector 634 is welded tothe first output 660. Flange connector 610 is welded to the secondoutput 662. Flange connector 608 is welded to the third output 664.

Flange connectors 620 and 622 are connected to join the first linear gasline 638 to the first three-way valve 642. Flange connectors 624 and 626are connected to join the first three-way valve 642 to the second lineargas line 640. Flange connectors 628 and 630 are connected to join thesecond linear gas line 640 to the second three-way valve 644. Flangeconnectors 632 and 634 are connected to join the second three-way valve644 and the third three-way valve 646.

In the embodiment of FIG. 6, only straight gas lines are used. Althoughelectropolishing of non-linear sections is commercially available, theuse of straight gas lines facilitates the electropolishing of the innersurface of the lines, which necessitates inserting an electrode in thecenter of the gas lines. Also, in the embodiment of FIG. 6 and in otherembodiments of the invention, multi-way valves are used instead oftee-fittings, which reduces the number of weldments in the system andeliminates the dead zones created by tee-fittings, and thus, potentialcontamination nucleation sites in the system are minimized.

Gas lines according to embodiments of the invention, such as the firstlinear gas line 638 and the second linear gas line 640, wereelectropolished for 1, 3, or 4 minutes and cross-sectioned to allowinspection of the interior surfaces of the gas lines at differentregions, including the weldment zone areas, the flange connector areas,the heat affected zone areas, and the remaining regions of the gaslines. FIG. 3 is a graph that shows the resulting average Ra valuesobtained at the weldment zone areas, the glands, and the remainingregions of the gas lines after electropolishing was performed. Theelectropolished regions had improved, smoother surfaces thancorresponding non-electropolished regions. Theelectropolishing-generated improvement in the surface texture of theweldment zone areas was significant and detectable by the naked eye.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A system of gas lines for a processing chamber, comprising: one ormore electropolished valves that are three-way valves or higher andcomprise outputs, wherein each output of each valve is welded to aflange connector; and one or more electropolished linear gas lines,wherein each of the electropolished linear gas lines comprises: a firstend; a second end; a first flange connector welded to the first end; anda second flange connector welded to the second end, wherein either thefirst or second flange connector of each of the one or moreelectropolished linear gas lines is connected to one of the flangeconnectors welded to the one or more electropolished valves.
 2. Thesystem of claim 1, wherein the processing chamber is a chemical vapordeposition chamber attached to one of the flange connectors, and anotherof the flange connectors is connected to an aluminum source.
 3. Thesystem of claim 1, wherein the one or more electropolished valves arethree-way valves.
 4. The system of claim 1, wherein the one or moreelectropolished valves are four-way valves.
 5. The system of claim 1,wherein the one or more electropolished valves comprise a firstelectropolished three-way valve, a second electropolished three-wayvalve, and a third electropolished three-way valve, with each of theelectropolished three-way valves having a first, second, and thirdoutput, wherein the first output is welded to a first flange connector,the second output is welded to a second flange connector, and a thirdoutput is welded to a third flange connector, and the one or moreelectropolished linear gas lines comprise a first electropolished lineargas line and a second electropolished linear gas line.
 6. The system ofclaim 5, wherein the flange connector of the first output of the firstelectropolished three-way valve is connected to the first flangeconnector of the first electropolished linear gas line, the flangeconnector of the second output of the first electropolished three-wayvalve is connected to the first flange connector of the secondelectropolished linear gas line, the second flange connector of thesecond electropolished linear gas line is connected to the flangeconnector of the first output of the second electropolished three-wayvalve, the flange connector of the second output of the secondelectropolished three-way valve is connected to the flange connector ofthe first output of the third electropolished three-way valve.
 7. Thesystem of claim 6, wherein the first electropolished three-way valveconnects the first electropolished linear gas line and the secondelectropolished linear gas line at an angle.
 8. The system of claim 7,wherein the angle is about 90°.
 9. A system of gas lines for aprocessing chamber, comprising: two or more electropolished linear gaslines comprising a first gas line and a second gas line, wherein thefirst gas line and the second gas line are connected at an angle by anelectropolished valve that is a three-way valve or higher and comprisesfirst and second outputs, wherein the first gas line is connected to thefirst output of the electropolished valve by a first flange connector onthe first output of the electropolished valve, and the second gas lineis connected to the second output of the electropolished valve by asecond flange connector on the second output of the electropolishedvalve.
 10. The system of claim 9, wherein the one or moreelectropolished valves are three-way valves.
 11. The system of claim 9,wherein the one or more electropolished valves are four-way valves. 12.The system of claim 9, wherein one of the electropolished linear gaslines is connected to a second electropolished valve, and anotherelectropolished linear gas line is connected to a source of aluminum.13. The system of claim 12, wherein the second electropolished valve isconnected to the processing chamber.
 14. The system of claim 13, theprocessing chamber is an aluminum chemical vapor deposition chamber. 15.The system of claim 14, wherein the second electropolished valve isfurther connected to a third electropolished valve.
 16. A method offorming a gas line system for a processing chamber, comprising:obtaining one or more electropolished valves that are three-way valvesor higher and comprise outputs, wherein each output of each valve iswelded to a flange connector, and one or more electropolished linear gaslines, wherein each of the electropolished linear gas lines comprises: afirst end; a second end; a first flange connector welded to the firstend; a second flange connector welded to the second end; and thenjoining at least one of the electropolished valves to at least one ofthe electropolished linear gas lines by coupling one of the flangeconnectors on the at least one electropolished valve to the first flangeconnector on the at least one electropolished linear gas line.
 17. Themethod of claim 16, wherein the one or more electropolished linear gaslines comprises two electropolished linear gas lines, and joining atleast one of the electropolished valves to at least one of theelectropolished linear gas lines comprises joining one of theelectropolished valves to the two electropolished linear gas lines. 18.The method of claim 17, wherein joining one of the electropolishedvalves to the two electropolished linear gas lines comprises joining theelectropolished valve to the two electropolished linear gas lines at anangle.
 19. The method of claim 18, wherein the angle is approximately900.
 20. The method of claim 18, wherein the one or more electropolishedlinear gas lines are electropolished for between about 3 minutes andabout 4 minutes.